1. Field of the Invention
This invention relates to a device for measuring a proportion of body fat and its weight as well as measuring one body weight, for health management or monitoring.
2. Description of the Prior Art
Technologies for measuring weight of body fat contained in one body by measuring weight and impedance of his/her body have been proposed.
For example, Japanese Patent Publication No. Hei 5(1993)-49050 discloses a body fat scale comprising a weighing platform for weighing a body weight; a body weight measuring part for converting electric signals from the weighing platform into body weight signals; and two feet use electrodes which are electrically connected to an impedance measuring part and are adapted to contact with soles of one feet to be measured, respectively. The two electrodes are integrally built in the weighing platform in such a manner as to be electrically insulated from each other.
This body fat scale is designed to incorporate the electrodes in a surface of the weighing platform so that with one simple mounting the weighing platform with one bare feet, the one body weight and impedance can both automatically measured.
It is also designed to have a key-input part for additionally entering therein personal information, such as age and sexuality, necessary for accurate calculation of weight of body fat from the body weight and impedance of one body.
In this conventional body fat scale, the two electrodes, i.e., the right-foot-use electrode and the left-foot-use electrode, are fixedly arranged on and integrated with the weighing platform. With this arrangement, there is a limited space between the two electrodes and, accordingly, inner thighs of a user are subject to contact with each other, depending on the user physical constitution.
When the inner thighs contact with each other during the measurement of impedance of one body, the route for electric current to pass from the right-foot-use electrode to the left-foot-use electrode by way of one body is short-circuited at the contacting part of the thighs. As a result of this, two routes, i.e., a first route for electric current to pass through the one body and a second route as short-circuited at his/her thighs, are presented in the form of a parallel circuit, which causes an error by rendering the impedance lower than the first route only. For this reason, with this conventional arrangement of two built-in electrodes being arranged with a limited space therebetween, the error sometimes becomes some tens of percents.
It has been proven that improved accuracy of measurement of the impedance is provided by a standing posture with one""s right and left feet spread out to some extent. This seems to be because, since the standing posture with one both feet spreading out produces a balanced posture with little stagger and thus produces little variation in pressure at the joints, whereby the impedance is stabilized and thus the measurement of the body fat is also stabilized.
Thus, the impedance should desirably be measured in the standing posture with the right and left feet straddling or spread out to some extent. The two built-in electrodes arrangement has the disadvantage, however, that the spreading of the space between the two electrodes will involve the upsizing of the entire device and thus the increasing of storage space for the scale to use at home, thereby resulting in the disadvantage of difficulty of use.
In addition, the conventional arrangement in which the two electrodes are built in the weighing platform has the following disadvantages in repair and replacement. When deterioration, damage or failure of the electrode surface occurs, it is hard to replace only the damaged electrode with a new one. Also, in the state in which the electrodes are removed from the scale, the scale can no longer be used as a weighing machine.
The present invention is made with the aim to provide improved accuracy of measurement of body fat in a separable fat scale in which a body weight measuring part and an electrode part are separately arranged.
The present invention provides a separable fat scale comprising a body weight measuring part for detecting a body weight of a person under test who mounts a weighing platform; electrode parts having thereon at least a pair of electrodes to electrically contact with soles of feet of the person under test and formed separately from the weighing platform; an impedance measuring part for measuring impedance of the person under test through his/her soles contacting with the electrodes; an input part for inputting personal data including information about physical characteristics of the person under test such as sexuality, age and body height; an arithmetic part for calculating a proportion of body fat in the body of the person under test and/or weight of the body fat under impedance signals obtained from the impedance measuring part, load signals obtained from the body weight measuring part and the personal data input; and a data output part for outputting the calculated proportion of body fat in the body and/or weight of the body fat, wherein the electrode parts are separated into a right-foot-use electrode part and a left-foot-use electrode part to be separately arranged. With this arrangement, the electrode parts can be spaced apart so that inner thighs of the person under test can be prevented from contacting each other, thus producing the effect of providing improved accuracy of measurement of the body fat.
The physical characteristics which maybe selectively input as the personal data include not only sexuality, age, body height and crotch height of the person under test but also a length between outstretched hands, a length from navel to sole, girth of an arm, girth of thighs, girth of lower thighs, girth of a breast, girth of an abdominal part, girth of a lumbar part, and sitting height. In accordance with this personal information, some components, such as coefficients of the conversion equation in the arithmetic part can be modified to calculate the proportion of body fat with further accuracy.
The input part and the data output part may selectively be arranged on the body weight measuring part side or on the electrode part side.
Also, the data output part maybe realized by visual information output means (display panel and the like) or audible information output means (synthetic voice output device and the like).